Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon. Many integrated circuits are typically manufactured on a single semiconductor wafer, and individual dies on the wafer are singulated by sawing between the integrated circuits along a scribe line. The individual dies are typically packaged separately, in multi-chip modules, for example, or in other types of packaging.
In semiconductor technology, Group III-Group V (or III-V) semiconductor compounds are used to form various integrated circuit devices, such as high power field-effect transistors, high frequency transistors, high electron mobility transistors (HEMTs), or metal-insulator-semiconductor field-effect transistors (MISFETs). The HEMTs have a number of attractive properties including high electron mobility and the ability to transmit signals at high frequencies.
Although existing HEMTs have generally been adequate for their intended purpose, they have not been entirely satisfactory in all respects.